Content caching devices or web-caches that cache frequently viewed web pages, pictures and multi-media content are deployed in the internet for reducing transport latencies, and reducing download times for frequently accessed content across the internet. Similarly, web-proxies/caches are also deployed at enterprise sites to cache frequently used Internet web-content within the enterprise network.
Caching devices 10 can also be used in mobile wireless network, for example, a 3G/UMTS network 20. The wireless network includes a Radio Access Network (RAN) 21 and a Core Network (CN) 22. A typical wireless network is shown in FIG. 1.
The GGSN 3 (Gateway GPRS Service Node) connects the mobile wireless network to the IP Core Network. The Gateway GPRS Support Node (GGSN) 3 is a main component of the GPRS (General Packet Radio Service) network. The GGSN 3 is responsible for compatibility between the GPRS network and external packet switched networks, such as the Internet 1 and X.25 networks.
When viewed from an external network, the GGSN 3 appears as a router to a sub-network, because the GGSN 3 hides the GPRS infrastructure from the external network. When the GGSN 3 receives data addressed to a specific user, it checks if the user is active. If it is, the GGSN 3 forwards the data to the SGSN 4 serving the mobile user. However if the mobile user is inactive, the data are discarded, or a paging procedure is initiated to locate and notify the mobile device. For data originated within the GPRS network, the GGSN 3 routes these mobile-originated packets to the correct external network.
The GGSN 3 converts the GPRS packets coming from the SGSN 4 into the appropriate packet data protocol (PDP) format (e.g., IP or X.25) and sends them out on the corresponding packet data network. For incoming packets, the PDP addresses are converted to the GSM address of the destination user. The readdressed packets are then sent to the responsible SGSN 4. In order to accomplish this function, the GGSN 3 stores the current SGSN address of the user and its associated profile in its location register. The GGSN 3 is responsible for IP address assignment and is the default router for the connected user equipment (UE) 7. The GGSN 3 also performs authentication functions.
A Serving GPRS Support Node (SGSN) 4 is responsible for the delivery of data packets from and to the mobile stations within its geographical service area. Its tasks include packet routing and transfer, mobility management (attach/detach and location management), logical link management, and authentication and charging functions. The location register of the SGSN 4 stores location information and user profiles of all GPRS users registered with this SGSN 4.
The Radio Network Controller (or RNC) 5 is a governing element in the radio access network and is responsible for controlling the Node Bs 6 that are connected to it. The RNC 5 carries out radio resource management, some of the mobility management functions and is the point where encryption is done before user data is sent to and from the mobile. The RNC 5 connects to the SGSN (Serving GPRS Support Node) 4 in the Packet Switched Core Network.
Node B 6 is a term used to denote the base transceiver station (BTS) in the UMTS/3GPP Architecture. As in all cellular systems, such as GSM, Node B (or BTS) 6 contains radio frequency transmitter(s) and the receiver(s) used to communicate directly with the user equipment, which move freely around it.
The user equipment (UE) 7 comprises all user equipment, including handsets, smart phones and computing equipment.
Radio Access Networks (RANs), such as in GSM/GPRS, 3G/UMTS/HSDPA/HSUPA, LTE, CDMA network etc., have their own private networks (PLMN) and interconnect to the Internet/IP networks through gateway devices (GGSN in GSM/GPRS, 3G/UMTS/HSDPA/HSUPA, and PDSN in CDMA). Content caches 10 are typically deployed outside of the RAN as shown in FIG. 1. However, content caches 10 are not deployed in the RAN between the Wireless Base Station 6 and GGSN 3 or PDSN (in a CDMA Network).
One reason for this is, while the user application payloads are TCP/IP, those payloads are embedded within Radio Access Network Protocols that are specific to the specific RAN. Thus, within the RAN, application payloads are not directly visible for performing content-aware caching and other optimizations. The RAN network 20 is deployed as a transport network that transports user IP traffic (Bearer IP traffic) using either ATM or IP transports. Regardless of the type of transport, the RAN network transports the user payloads in per user/per service tunnels. Such tunnels are terminated within the PDSN or GGSN 3, which forwards the bearer IP traffic to the public IP network using IP forwarding rules. Thus in the prior art deployments, the RAN network is content un-aware.
Content caching devices cache content when a client device accesses an object (such as a web page or a URL object), for subsequent delivery if the same content is requested by the same or a different user. Thus, cache updates are triggered by client accesses. Web crawlers and other mechanisms proactively fetch content to increase cache hit ratios and other features, such as content searching functions, etc. Content Delivery Network devices proactively retrieve content from specific content servers through the internet before such content is requested by any user. Such pre-fetching reduces the latency while delivering content when requested by one or more users, and assists in delivering dynamic content for Edge Side Includes (ESI) by CDNs. Also, content servers (origin servers) redirect user requests to appropriate CDN devices through interaction with the CDN Network using DNS. While such mechanisms exist in the internet and wire-line networks, in wireless mobile networks, connections to internet data-plane sessions are established only when a user accesses the packet network (internet or private network).
Co-pending Patent Publication No. 2010/0034089, entitled “Content Caching in the Radio Access Network”, filed Aug. 6, 2009, the contents of which are incorporated by reference, proposes deploying Content Aware Ran Caches in the Radio Access Network at one or more locations. A RAN-cache may be placed in a Radio Access Network, such as UMTS or LTE, where it is used to cache frequently accessed content by one or more users in local storage and serves the cached content to plurality of users per HTTP Protocols. The RAN-cache device operates as a transparent inline cache, in the sense that it intercepts the Control Plane and User Plane Protocols on the interfaces to which it is connected. It then reconstructs the objects and their corresponding references.
It would be advantageous if content could be pre-fetched before any user requests the content. It would be beneficial if this pre-fetched data could be stored in a RAN cache, for subsequent use by attached mobile users.